Morton International, Inc.

Morton Thiokol Inc.

Leo Roos

James J Briguglio

Jose L Correa

Robert C Stumpf

Charles L Farnum

Fredrick J Axon

Clancy P Crooks

James G Shelnut

Robert A Barr

Amedeo Candore

Lawrence Crane

Thomas P Carter

Frederick J Axon

Lawson Lightfoot

Samuel W Shoemaker

Melvin A Lipson

Daniel A Frazer

A dry film for forming a solder mask includes a cover sheet, a photoimageable composition layer which is curable to form a solder mask and a top coat interposed between the cover sheet and the photoimageable composition layer which is selectively adherent to the photoimageable composition layer. The dry film is applied to a surface of a printed circuit board with a minor portion of the area of the photoimageable composition layer tacked to the printed circuit board. The cover sheet is peeled away. With heat and vacuum, the photoimageable composition layer is laminated to the irregular surface of the printed circuit board, conforming the photoimageable composition layer to the contours thereof and leaving the top coat as a protective covering over the photoimageable composition layer. The photoimageable composition layer is exposed to patterned actinic radiation, developed and cured to form a hard, permanent solder mask.

Dry film photoresist for forming a conformable mask and method of

A dry film for forming a solder mask includes a cover sheet, a photoimageable composition layer which is curable to form a solder mask and a top coat interposed between the cover sheet and the photoimageable composition layer which is selectively adherent to the photoimageable composition layer. The dry film is applied to a surface of a printed circuit board. With heat, vacuum and mechanical pressure, the photoimageable composition layer is laminated to the irregular surface of the printed circuit board, partially conforming the photoimageable composition layer to the contours thereof. Within about 60 seconds and with the photoimageable composition layer still heated, the cover sheet is peeled away, leaving the top coat as a protective covering over the photoimageable composition layer. Removal of the cover sheet allows the photoimageable composition layer to fully conform to the contours of the printed circuit board. Immediately thereafter, the circuit board is cooled to about ambient temperature or below. The photoimageable composition layer is exposed to patterned actinic radiation, developed, and cured to form a hard, permanent solder mask.

Method of application of a conforming mask to a printed circuit board

Apparatus for wet laminating a photopolymerizable film onto circuit board panels or other substrates. The apparatus is easily and quickly convertible from dry laminating to wet laminating with the rollers therefor mounted in bearing blocks which are insertable in slots in brackets at each end and removable therefrom. The lower roller thereof has a gear the teeth of which are meshable with the teeth of an idler gear for transmission of rotation power thereto. Elongate tubes for applying a fluid, which comprises between about 0.1 and about 10 wt. % of a heterocyclic metal-chelating agent, to the wet insertion rollers for application thereof to the panels are contained in a yoke which is adjustable next to wet insertion rollers for wet laminating or away from dry insertion rollers for dry laminating. The flow rate of fluid to the elongate tubes is controlled, and excess fluid applied to the wet insertion rollers is collected in a tray and returned to the system in order to prevent waste and undesirable environmental effects.

Wet lamination process and apparatus

Apparatus for wet laminating a photopolymerizable film onto circuit board panels or other substrates. The apparatus is easily and quickly convertible from dry laminating to wet laminating with the rollers therefor mounted in bearing blocks which are insertable in slots in brackets at each end and removable therefrom. The lower roller thereof has a gear the teeth of which are meshable with the teeth of an idler gear for transmission of rotation power thereto. Elongate tubes for applying a fluid, which comprises between about 0.1 and about 10 wt. % of a heterocyclic metal-chelating agent, to the wet insertion rollers for application thereof to the panels are contained in a yoke which is adjustable next to wet insertion rollers for wet laminating or away from dry insertion rollers for dry laminating. The flow rate of fluid to the elongate tubes is controlled, and excess fluid applied to the wet insertion rollers is collected in a tray and returned to the system in order to prevent waste and undesirable environmental effects. In accordance with an alternative embodiment, fluid is applied to a substrate by a first pair of insertion rollers and the amount of fluid retained on the substrate is regulated by applying and regulating a pressure between a second pair of insertion rollers and the substrate. The lower of the first pair of insertion rollers, which transmits driving force to the second pair of insertion rollers, comprises a roller member removably attached to a pair of fixedly mounted stub shafts so that it may be easily removed and replaced for conversion between wet and dry lamination.

A photoimageable composition of the negative acting type which includes a binder polymer which contains carboxyl groups is provided with a metal chelate in which the coordination number of the metal is 2 or higher. When the photoimageable composition is coated as a layer on a dry film, the metal chelate reacts with the carboxyl groups of the polymer, releasing a metal ion which bridges carboxyl groups of two or more polymer molecules. This bridging reduces cold flow of the photoimageable composition layer of the dry film.

Photoimageable composition with reduced cold flow due to salt-bridging

Photoinitiator compositions are disclosed which contain 3,3'-carbonyl bis(7-diethylaminocoumarin); an alkyl ester of a p-dialkylamino benzoic acid; and either camphorquinone or a 2,4,5-triphenylimidazolyl dimer. Photoinitiators are also provided which contain 3,3'-carbonyl bis(7-diethylaminocoumarin); an alkyl ester of a p-dialkylamino benzoic acid; camphorquinone and a 2,4,5-triphenylimidazolyl dimer. These latter photoinitiators are particularly useful in photopolymerizable compositions which are polymerized by exposure to visible laser light.

Photoinitiator composition containing bis ketocoumarin dialkylamino

Method of forming a conformable mask on a printed circuit board

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Laguna Beach, CA, United States of America

Leo Roos